Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, monolithic windows, and/or the like.
Conventional low-E coatings are disclosed, for example and without limitation, in U.S. Pat. Nos. 6,576,349, 9,212,417, 9,297,197, 7,390,572, 7,153,579, and 9,403,345, the disclosures of which are hereby incorporated herein by reference.
Certain low-E coating utilize at least one transparent dielectric layer of titanium oxide (e.g., TiO2), which has a high refractive index (n), for antireflection and/or coloration purposes. See for example U.S. Pat. Nos. 9,212,417, 9,297,197, 7,390,572, 7,153,579, and 9,403,345. Although high refractive index dielectric material TiO2 is known and used in low-E coatings, TiO2 has a very low sputter-deposition rate and is not thermally stable upon heat treatment such as thermal tempering of about 650 C for 8 minutes, due to film crystallization (or change in crystallinity) in as-deposited or post-tempering state, which may in turn induce thermal or lattice stress on adjacent layers in the film stack. Such stress can further cause change in physical or material properties of the stack and hence impact on the Ag layer, which results in deteriorated low E stack performance. The low sputter deposition rate of TiO2 leads to significantly high costs associated with making low-E coatings including such layer(s).
Example embodiments of this invention solve these problems by providing a high index (high refractive index value n, measured at 550 nm) and low absorption (low k value, measured at 400 nm) multilayer film in a low-E coating, wherein the overall high index multilayer film has a higher sputter deposition rate than solely TiO2 of like thickness, the overall high index multilayer film has improved thermal stability compared to TiO2 of like thickness, and use of the overall high index multilayer film does not significantly adversely affect optical performance of the low-E coating compared to use of TiO2 of like thickness. Example embodiments of this invention relate to a coated article including a low emissivity (low-E) coating having at least one infrared (IR) reflecting layer of a material such as silver, gold, or the like, and at least one high refractive index dielectric bi-layer film. The high index dielectric bi-layer film may be of or include a first high index layer of or including ZrSiN and/or ZrSiAlN, and a second high index layer of or including titanium oxide (e.g., TiO2), which has been found to improve deposition rate of the coating and also improve/raise solar heat gain properties of the coated article in monolithic or IG applications. The first high index layer of or including ZrSiN and/or ZrSiAlN may be amorphous or substantially amorphous, and the second high index layer of or including titanium oxide may be substantially crystalline in certain example embodiments, with the amorphous aspect helping the low-E coating to better withstand optional heat treatment (HT) such as thermal tempering. The high index dielectric bi-layer film has a faster sputtering rate than TiO2 at like thickness, as the ZrSiN and/or ZrSiAlN portion of the bi-layer film has a significantly faster sputter deposition rate than TiO2, thereby leading to lower costs associated with producing low-E coatings. The high index bi-layer film may be a transparent dielectric high index layer in preferred embodiments, which may be provided for antireflection purposes and/or color adjustment purposes, in addition to having thermal stability. In certain example embodiments, the low-E coating may be used in applications such as monolithic or insulating glass (IG) window unit, vehicle windows, of the like.
In an example embodiment of this invention, there is provided a coated article including a coating supported by a glass substrate, the coating comprising: a first dielectric film on the glass substrate; an infrared (IR) reflecting layer on the glass substrate, located over at least the first dielectric film; a second dielectric film on the glass substrate, located over at least the IR reflecting layer; and wherein at least one of the first and second dielectric films comprises (a) a first high index dielectric layer comprising a nitride of Zr and Si, wherein the first high index dielectric layer contains more Zr than Si, and (b) a second high index dielectric layer comprising an oxide of titanium that directly contacts the first high index dielectric layer.